Primary Risk Drivers
Below is a snapshot of domains that materially influence the MARA Rating.
Clinical effectiveness
The evidence indicates comparable efficacy to existing options, primarily derived from single-arm studies without active control. The STR1VE-US and START studies show strong absolute outcomes, but the lack of randomized trials limits the confidence in comparative efficacy against standard of care. The evidence is compelling for symptomatic infantile-onset SMA type 1 but lacks robustness for broader populations.
Cost effectiveness
The cost-effectiveness analysis shows that onasemnogene abeparvovec is costly compared to its benefits, with ICER estimates indicating it exceeds acceptable thresholds. The economic models are based on assumptions rather than direct trial evidence, leading to uncertainty in the cost-effectiveness conclusions.
Quality of life
There is a significant absence of direct HRQoL measurement in clinical trials for onasemnogene abeparvovec. NICE explicitly states that no validated instruments were used to capture changes in HRQoL. While some caregiver-reported outcomes exist, they do not equate to utility-based trial HRQoL endpoints, leading to a lack of meaningful evidence.
Supporting Domains
Safety and Adverse Effects
The safety profile indicates acceptable risks with manageable adverse events, although there are notable concerns such as elevated liver enzymes and serious liver injury. The long-term follow-up suggests no late-emerging major safety signals, but ongoing monitoring is required due to potential serious adverse effects.
Comparator Selection
The evidence primarily relies on historical controls rather than active comparators, which weakens the comparative analysis. While nusinersen is recognized as a key comparator, the lack of head-to-head trials limits the ability to draw definitive conclusions about relative effectiveness.
Patient Population and Subgroups
The trial populations are highly representative of the intended patient population, particularly for very young infants with type 1 SMA. However, there are limitations in subgroup analyses for older patients, which may affect generalizability.
Care Pathway Integration
Onasemnogene abeparvovec can be integrated into existing care pathways with some adjustments, particularly in monitoring and treatment protocols. The requirement for genetic testing and monitoring adds complexity but is manageable within current frameworks.
Resource Use and Cost Implications
The implementation of onasemnogene abeparvovec involves significant resource use, particularly due to the need for specialized centers and monitoring. While the treatment is single-administration, the overall cost burden is high, raising concerns about affordability.
Evidence Quality and Robustness
The evidence base is weaker than typical phase 3 packages, with non-randomized, single-arm studies and high risk of bias. The lack of robust comparative data and reliance on observational studies contribute to significant uncertainty in the evidence quality.
Uncertainty, Sensitivity, and Broader Impacts
There are notable uncertainties regarding the long-term effectiveness and safety of onasemnogene abeparvovec, particularly in broader populations. The potential for inequities in access to treatment based on genetic testing and screening adds to the complexity of the decision-making context.
